Currently gases such as oxygen can be determined by so-called planar Clark-type sensors wherein a sensing electrode and a reference electrode are deposited on a substrate using conventional semiconductor device fabrication techniques and a hydrogel layer is utilized as the electrolyte. A gas permeable membrane may cover the hydrogel layer and the electrodes. The oxygen to be determined in such a structure must pass through the membrane, dissolve in the hydrogel, pass through the hydrogel, and finally contact the sensing electrode. As a result, the response time of such electrodes is not as fast as might be desired. In fact, even the fastest sensing of this type of sensor, when made on a microscale, has a response time of at least five seconds and often ten seconds or more. Furthermore, such sensors are generally used only to determine oxygen and are not used, generally, for determining the concentrations of a number of gaseous species.
It would be highly desirable to have a faster responding gas sensor, or an array of such sensors, which could be made selectively sensitive to any of a number of different gaseous species.
The present invention is directed to overcoming one or more of the problems as set forth above.